With the further growth of the urban population, traffic jam has become the nuisance of every main city. Although public transportation is a very effective solution to the traffic jam, a last kilometer problem, that is, a relatively long final walking distance, still remains, which is one of the factors hindering the building of a perfect bus system. Traditional roller skates can solve the above-mentioned problem to a certain extent, and there are various electric transportation tools on the market, such as electric roller skates appearing recently, which are the solutions to the last kilometer problem.
However, the existing electric roller skates have one problem that: an enough space must be reserved between shoe soles and the ground because transmission structures are not small enough, resulting in a relatively long distance between vamps and the ground; and furthermore, the wheel tread is relatively small, so that the stability is extremely low, and only those who are skilled at roller skating can use the electric roller skates successfully. If the wheel tread is increased, two feet would collide with each other to cause falling over during walking due to extremely wide vamps, so that the electric roller skates are very unsafe to use on the road.